1. Field of the Invention
This invention relates to methods for the detection and monitoring of mast-cell mediated inflammatory disease states. The invention includes methods for the detection and monitoring of inflammatory diseases associated with the respiratory tract, such as asthma.
2. Background of the Invention
Inflammation, both acute and chronic, is a major contributor to a wide variety of mammalian disease states. Several diseases, such as asthma, have now been linked to the presence of an inflammation-related condition.
One initiator of the inflammatory sequence is an allergic response to inhaled allergens. Leukocytes carrying IgE receptors, notably mast cells and basophils, but also including monocytes, macrophages, and eosinophils, are present in the epithelium and underlying smooth muscle tissues of bronchi where they are activated initially by binding of specific inhaled antigens to the IgE receptors. Activated mast cells release a number of preformed or primary chemical mediators of the inflammatory response and enzymes. In addition, several large molecules are released by degranulation of mast cells: proteoglycans, peroxidase, arylsulfatase B, and notably the proteases tryptase and chymotryptic proteinase (chymase). See, DRUG THERAPY OF ASTHMA, pp. 1054-54.
This chemical release from mast cells probably accounts for the early asthmatic response that occurs in susceptible individuals after exposure to airborne allergens. The late asthmatic reaction is accompanied by a marked increase in the number of inflammatory cells infiltrating bronchiolar smooth muscle and epithelial tissues, and spilling into the airways. These cells include eosinophils, neutrophils, and lymphocytes, all of which are attracted to the site by release of mast cell derived chemotactic agents.
Tryptase is the major secretory protease of human mast cells and is proposed to be involved in neuropeptide processing and tissue inflammation. Mature human tryptase is a glycosylated, heparin-associated tetramer of heterogenous, catalytically active subunits. See, e.g., Vanderslice et al. Proc. Natl. Acad. Sci. USA 87:3811-3815 (1990); Miller et al., J. Clin. Invest. 86:864-870 (1990); Miller et al. J. Clin. Invest. 84:1188-1195 (1989); and Vanderslice et al. Biochemistry 28:4148-4155 (1989).
Tryptase is stored in mast cell secretory granules. After mast cell activation, human tryptase can be measured readily in a variety of biologic fluids. For example, after anaphylaxis, tryptase appears in the bloodstream, where it remains detectable for several hours. See, Schwartz et al., N. Engl. J. Med. 316:1622-1626 (1987). Its appearance has been detected in samples of nasal and lung lavage fluid from atopic subjects challenged with specific antigen. See, Castells and Schwartz, J. Allerg. Clin. Immunol. 82:348-355 (1988) and Wenzel, et al., Am. Rev. Resp. Dis. 141:563-568 (1988). Tryptase levels in lung lavage fluid obtained from atopic asthmatics increase after endobronchial allergen challenge.
Anti-tryptase antibodies have been prepared by injecting tryptase from rats into rabbits and isolating the polyclonal rabbit anti-tryptase IgG fraction. The ability of this IgG fraction to inhibit HIV infection and syncytia formation was tested ("Anti-tryptase antibody and composition for treatment of AIDS using the same", Katunama et al., EP 0 379 295). The same investigators reported a human tryptase-like protein isolated from human lymphoblastic leukemia cells ("Human tryptase-like protein", Katunama et al., EP 0 419 292) and prepared polyclonal rabbit antisera against this human tryptase-like protein.
Several diseases have been traced to an immune response mounted by the body against its own normal, endogenous body constituents. These diseases are generally termed autoimmune diseases and include systemic lupus erythematosus (SLE), insulin dependent diabetes and Addison's disease. Frequently, an autoimmune disease is characterized by the presence of autoantibodies against a specific normal, endogenous body constituent(s). For example, multiple sclerosis has been associated with the presence of autoantibodies against myelin basic protein; peripheral neuropathies with the presence of autoantibodies against nervous system glycolipids and glycoproteins (GA1, GM2 and GM2 and MAG) and systemic lupus erythematosus with the presence of autoantibodies against the Sm antigen.
Mast cell mediated inflammatory conditions are a growing public health concern. In particular, asthma has become a common chronic disease in industrialized countries. Therefore, it would be desirable to provide improved methods of detecting such inflammatory disease, both to select an appropriate therapy and to monitor the effectiveness of a chosen therapeutic regimen. In addition, it would be desirable to have prognostic tools to detect the onset of inflammation before progression of the disease to the symptomatic state. This invention fulfills this and related needs, partly by detecting the presence of autoantibodies against mast cell specific proteins.